a) Field of the invention
The present invention is concerned with improvements to the meat processing machines called in the trade "middle splitters", which machines are used in the food industry for splitting middles into loins and bellies.
b) Brief description of prior art
In the meat processing industry, it is of common practice to split the carcass of each processed animal along the spine thereof, in order to divide this carcass into two symmetrical parts, called "middles". Usually, such a splitting is carried out after the shoulders and hinds have been removed.
Each middle which is so obtained includes half of the longitudinally splitted spine and the adjacent ribs, loin and belly. In order to obtain various cuts for retail purposes such as chops, ribs and fillets, the middle must then be splitted into a loin and a belly by cutting it parallel to the spine. Such a cutting is made with a machine called "middle splitter".
FIG. 1 identified as prior art, is a perspective view of a middle "M" before it is cut into a loin "L" and a belly "B". The cutting line is shown in dotted line.
Traditionally, middles were split manually with a ribbon saw. The middles were guided through the saw by an operator in order to follow the curved shape of the spine. This method, even though efficient, was labour-intensive.
In order to automate the process and obtain a cut that ultimately respects the curved shape of the spine, middle splitters have been devised. Such machines are devised to straighten the spine before it is split, so that the cutting can be accomplished quickly and efficiently with a circular saw.
After the middle is split, the spine recovers its natural curve. This explains why the dotted line shown in FIG. 1 is not straight. Then, the loin portion "L" that has been cut proceeds to another station in order to be cut it into a fillet and chops. The belly "B" also proceeds to another station, where the ribs "R" are lifted out. In the case of pork, the remaining belly meat is used to make bacon by first smoking the meat and then slicing it into thin slices using a ribbon saw.
As aforesaid, middle splitters are already used in the industry. They basically comprise a work table onto which a slotted conveyor belt is mounted to move the carcass in a forward direction with the shoulder-adjacent end of the middle positioned forwardly. A circular saw substantially perpendicular to the conveyor belt, extends into the slot provided in the conveyor belt. This saw is positioned in such a manner as to cut the middle laid on the conveyor belt at a distance of 2 inches from the spine of the middle when the middle moves forwards. The middle splitter also includes a guide, parallel to the slot, slightly above the conveyor belt, to hold the middle fiat against the conveyor belt while it is cut by the saw.
A driving wheel having peripheral corrugations to engage the middle adjacent the spine, is rotatably mounted near the circular saw to pull the middle toward the circular saw while pushing the spine toward the adjacent guide. This driving wheel which is preferably conical in shape, is powered by a motor. The wheel exerts pressure on the spine by way of pressure-exerting means devised to push the wheel towards the guide to straighten the spine while the middle is cut so that a straight cut may be obtained. After the middle is split, the spine recovers its natural shape. The resulting cut is in practice equivalent to the one an operator would have obtained by manually splitting the middle with a ribbon saw, but with far greater efficiency.
So far, the driving wheel which, as aforesaid, is preferably conical, has a top diameter of approximately 22 inches and a bottom diameter of 16 inches. The bottom part is cylindrical and extends 2 inches towards the conveyor belt, just slightly above it.
If the middle splitters presently in use are efficient, there are still some problems associated with their use.
Removal of the shoulder from the middle is made by cutting. During such operation a portion "P" of the shoulder blade is often cut and remains in the middle, as shown in FIG. 1. When the middle subsequently proceeds through the middle splitter, the driving wheel which applies a constant pressure to the spine to straighten it also pushes on the portion of the shoulder blade that was left in the loin. Such causes this shoulder blade portion to be cut, and part of it to remain in the belly. When the bacon is sliced, this part of the shoulder-bone may snap the ribbon saw when it encounters it. Such slows down the process and is rather costly, as the ribbon saw must often be replaced.
Another problem associated with the existing middle splitter is that the guide, which is parallel to the slot, makes the entry of the middle into the splitter difficult. Furthermore, as the guide is rigidly mounted on the machine at a given distance from the conveyor belt, it does not allow for middles of different sizes and thicknesses to be easily processed. Thus larger middles will proceed through the splitter with greater difficulty as the guide cannot be adjusted.